*" THE NAUTILUS. 



and female shells indistinguishable. The breeding season seems 

 to fall in the winter months of the northern hemisphere. 



ELLIPTIC CALAMITARUM (Morelet) (?). 



This species has been mentioned incidentally by Frierson 

 (1. c., p. 15) from Rio Blanco, near Livingston, Guatemala, 

 collected Febr. 18, '13, but there is some doubt about the 

 identification; in a recent letter, Frierson thinks that this is 

 U. dysoni Lea. I do not want to express an opinion; the speci- 

 mens investigated by me belong to the same lot, and they have 

 absolutely the same structure of the soft parts as E. ortmanni. 

 Also the glochidia have the same shape and dimensions: L. 

 0.23, H. 0.22 mm. The breeding season also is in winter (glo- 

 chidia in February). 



ELLIPTIC YZABALENSIS (Crosse & Fischer) (Simpson Descript. 

 Catal. '14, p. 276). 



Two specimens, with soft parts, have been sent by A. A. 

 Hinkley, collected Jan. 6, '17, in Saja River, Guatemala (trib- 

 utary to Rio Dulce, below Lake Yzabal). Both are females, 

 and are gravid, but have not yet formed glochidia. 



Frierson thinks that these specimens might be a new species, 

 but they agree, in my opinion, quite well with Simpson's de- 

 scription of yzabalensis, and very well with v. Martens' figures 

 (Biol. Centr. Amer. Moll. 1900, p. 507, pi. 39, f. 9-11), and 

 in my identification I rely chiefly on 10 and 11 of these figures. 

 Their chief character is the great height of the shell as com- 

 pared with the length. One of my specimens has white, the 

 other has purple nacre. 



The anatomy is identical with that of E. ortmanni and calam- 

 itarum in every particular. Of course, the glochidia have not 

 been observed. 



There is no question that the three above species are closely 

 allied to each other, both in anatomy and shell characters (sul- 

 cated epidermis), and I should not be astonished if finally they 

 turn out to be forms of one and the same species. 



